We need audio converters initialized in SDL_InitAudio()

These are used separately from audio streams, e.g. SDL_OutputAudioThreadIterate(), so they should always be initialized when audio is initialized.

src/audio/SDL_audio.c

@@ -602,6 +602,9 @@ int SDL_InitAudio(const char *driver_name)
         SDL_QuitAudio(); // shutdown driver if already running.
     }
 
+    SDL_ChooseAudioConverters();
+    SDL_SetupAudioResampler();
+
     SDL_RWLock *device_list_lock = SDL_CreateRWLock();  // create this early, so if it fails we don't have to tear down the whole audio subsystem.
     if (!device_list_lock) {
         return -1;